Some posters showed Sir Alfred Hitchcock inserting the letter "L" into the word "Strangers" in the title to make "Stranglers".
In the scene where Ruth Roman and Patricia Hitchcock are watching the tennis match, Ruth gives Patricia a real U.S. ten dollar bill. Showing real U.S. money in movies then was illegal without permission from the U.S. Treasury Department. The Treasury Department later removed the prohibition for Psicosis (1960) and later movies.
The stunt where the man crawled under the carousel was not done with trick photography. Sir Alfred Hitchcock claimed that this was the most dangerous stunt ever performed under his direction, and he would never allow it to be done again.
As was his usual practice, Sir Alfred Hitchcock shot each scene so that there was only one way to edit it, which always conformed to his initial visual concept and pre-production storyboards.
Warner Bros. wanted their own stars, already under contract, cast wherever possible. In the casting of Anne Morton, Jack L. Warner got what he wanted when he assigned Ruth Roman to the project, over Sir Alfred Hitchcock's objections. Hitchcock found her "bristling" and "lacking in sex appeal" and said that she had been "foisted upon him".
Alfred Hitchcock: (at around 10 mins) The man boarding a train carrying a double bass as Guy disembarks.